This specification relates to classifying changes to resources.
Some resources on the World Wide Web are frequently updated, and some resources are rarely updated. Often a web site publisher will configure its web site to provide updates to users when the publisher updates a resource and deems the change significant. For example, the web site may generate a really simple syndication (RSS) document, or “feed” when a new news story is added to its homepage, and the RSS feed provides a brief synopsis of the news story. Alternatively, the web site will not generate a change notification for changes deemed to be of little or no significance, such as an update to a copyright notice to reflect a new year.
Aggregators are programs that allow users to subscribe to web feeds. Aggregators are client software installed on a computer or a web application accessible through a browser. Using the aggregators, users receive the change notifications, and can navigate directly to the resources for which the changes are indicated.
There are many resources, however, for which change notifications are not provided for any changes. For example, many sites do not provide RSS feeds that indicate new content, etc.